Broom snakeweed establishment following fire and herbicide treatments

Abstract

Broom snakeweed (Gutierrezia sarothrae [Pursh] Britt Rusby) propagation was monitored from 1990 through 1998 following burning and herbicide control practices conducted on blue grama (Bouteloua gracilis [H. B. K. Lag.]) grasslands near Corona, N.M. Broom snakeweed usually germinated in April, May, or June (83% of 394 total) and mostly in 1991 and 1992 (81% of total) when spring moisture was sufficient. The majority of broom snakeweed seedlings (52% of total) emerged the first or second year after summer burning, especially in areas where grass yield and cover declined and bare ground exposure increased as a result of intense fires. Spring fires caused less damage to blue grama than summer fires, and the number of broom snakeweed seedlings produced (18% of total) was similar to non-treated rangeland (22% of total), but lower than numbers on areas burned in the summer. Grass yield and cover increased within a year of herbicide spraying and treated plots had significantly (P 0.05) fewer broom snakeweed seedlings (8% of total) than burned and non-treated areas.